Optimization of a low-cost microfabrication technique for soft microelectrode mass production.

This master's thesis focuses on the modified production of flexible soft microelectrodes through the optimization of a state-of-the-art microfabrication process by reducing instrumental and manufacturing costs, while producing at the same time at large scale and maintaining the high degree of reproducibility of the conventional soft microelectrodes. The proposed approach aims to produce flexible microelectrodes that can be used as soft probes for Soft-Probe Scanning Electrochemical Microscopy (Soft-Probe SECM). A large range of process parameters are thoroughly varied and the soft probes analysed and compared with their conventional counter parts: first, by optical as well as electrical characterization and, subsequently, by standard electrochemical methods, such as cyclic voltammetry and chronoamperometry. Second, the soft probes are examined for their use as sensors for Soft-Probe-SECM, in particular by employing them for recording surface reactivity maps of substrates with conductive and insulating sections based on the local conversion of a redox couple in solution. The soft probes are activated by mechanical cutting of their cross-section, a process that exposes a microelectrode. Thereafter, the soft microelectrode is repetitively brushed in contact mode over the substrate surface in solution. Contact mode scanning enables the provision of a constant working distance between microelectrode and substrate surface without the need of a distance control system that is typically required with classical SECM using microelectrodes embedded in fragile glass bodies. The results obtained in this thesis provide a significant foundation for future developments in the production of flexible soft microelectrodes, contributing to the realization of advanced electrochemical devices with a more economical and practicable perspective.